This invention relates to a touch-up welding apparatus for a motorcar body assembly line for welding such portions, among many portions to be welded of a motorcar body, that remain unwelded after the body has passed along the main welding line.
Previously, it has been usual during the assembling of a motorcar body, that the side panels are temporarily or spot welded to a floor panel and a roof panel for a motorcar body. The resultant assembly is stepwise-conveyed along a main welding line, and during this stepwise-conveying, the assembly is additionally welded together by welding robots provided on side portions of each station on the line. It has been usual with this welding operation that there remain, as a result of a problem of the interference of the robots with the motorcar body, some portions which are unwelded, though a few, at such complicated or intricate portions as of the trunk, the roof rail, the fender or the like. These unwelded remainder portions are touch-up welded by a manual operation at the subsequent step.
To weld such unwelded remainder portions manually, as mentioned above, compels an operator to work in an unnatural, uncomfortable posture. Lower productivity results. Therefore, automatization of the touch-up welding is desired.
This invention has for its object to provide a touch-up welding apparatus meeting this desire.
According to this invention, for achieving the foregoing object, the invention includes a welding station into which a motorcar body having remaining unwelded portions thereof after passing through a main welding portion of the assembly line is positioned. Plural welding gun magazines for supporting respective differing welding guns are disposed adjacent a setting position for the motorcar body in the welding station. A framework surrounds the welding station and is provided with a welding robot mounted thereon. A robot main body of the welding robot is provided on the framework is movable laterally and longitudinally of the welding station. A wrist portion provided on a lower end of an upwardly and downwardly movable robot arm extending downwards from the robot main body is arranged so that each one of the respective welding guns on the respective gun magazines may be selectively attached thereto detachably for being replaceable one with another. In this manner, by replacing these welding guns one with another, such portions of the motorcar body that remained unwelded after passing through the main welding portion of the assembly line may be welded thereby.
Next, the operation of the foregoing apparatus will be explained as follows:
By moving the robot main body along the framework in the front and rear directions and in the right and left directions, and additionally, moving the robot arm upwards and downwards, the wrist portion on the lower end of the arm can be moved in a wide range without any interference thereof with the motorcar body. The remaining unwelded portions existing here and there extensively on the motorcar body can be welded, by replacing the welding guns between the wrist portion and the plural magazines.